

ABSTRACT

A fast crystallizing polyester composition comprising a block copolyester containing the repeating polymeric segments A and B wherein A is a polymeric segment of ethylene terephthalate units and B is a polymeric segment having a glass-transition temperature of less than 0 DEG  C. and preferably less than -20 DEG  C., the concentration of the segments of B being between 0.05 and 10 mole % of the block copolyester, and a crystallization nucleant which is an at least partially neutralized salt, preferably an alkali metal salt, of a polymer containing pendant neutralizable groups.



